The AFD has garbage autofocus. I used it in manual mode almost all the time. Eventually sold it and prefer the 645 pro. I think the newer AFDs have much better AF but still, you're not going to get anything nearly as good as Nikon AF, let's face it.
I did do some sports with the AFD but it was in manual focus mode!!! Yeah, the AF was just annoying. But I did find the focus confirmation very useful.
I would suggest going for 35mm for bumblebee work, when you need to move around a lot and focus quickly. And use 645 or go to a larger format e.g. 6x7 for the times that you can manually focus and compose at your leisure.
Different tools for different purposes. Too often people think they can treat a 645 like a 35mm and scan frames and get a bajillion pixels etc... nah, a 35mm camera is a completely different tool in almost every way. Don't feel guilty for selecting the tool best suited for a particular purpose. There are plenty of things I could only do with 35, and likewise there are things I could only do with a view camera. That's life.
If you must have an AF medium format camera and like the 35mm feel then consider the Fuji GA645Zi rangefinder. I have successfully done sports with that, even. It's noisy as heck but fun and way lighter and smaller than an AFD.